{"product_id":"hirth-hm-504-engine-manuals-collection","title":"Hirth HM 504 — Engine Manuals Collection","description":"\u003ch2\u003eHirth HM 504 — Engine Manuals Collection\u003c\/h2\u003e\u003cp\u003eA curated archival collection of primary-source technical documents covering the \u003cstrong\u003eHirth HM 504\u003c\/strong\u003e — the highly successful 4-cylinder inverted inline engine that became the standard powerplant for European light and trainer aircraft through the 1930s and 1940s, powering the iconic \u003cstrong\u003eBücker Bü 131 Jungmann\u003c\/strong\u003e and \u003cstrong\u003eArado Ar 79\u003c\/strong\u003e and training thousands of pilots across two continents.\u003c\/p\u003e\u003chr\u003e\u003ch3\u003eCollection Overview\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eTotal Unique Manuals: 8\u003c\/strong\u003e\u003cbr\u003eVariants covered: \u003cstrong\u003eA\u003c\/strong\u003e\u003c\/p\u003e\u003chr\u003e\u003ch3\u003eVariant A — 7 Manuals\u003c\/h3\u003e\u003ch4\u003eHM 504 A Operating and Maintenance\u003c\/h4\u003e\u003cul\u003e\u003cli\u003eHM 504 A Aircraft Engine Operating and Maintenance Manual 1936, \u003cem\u003eBetriebs- und Wartungsvorschrift\u003c\/em\u003e (German Language)\u003c\/li\u003e\u003c\/ul\u003e\u003ch4\u003eHM 504 A Installation and Assembly Instructions\u003c\/h4\u003e\u003cul\u003e\u003cli\u003eHM 504 A-2 Aircraft Engine Installation and Technical Data Documentation, \u003cem\u003eEinbauunterlagen\u003c\/em\u003e (German Language)\u003c\/li\u003e\u003c\/ul\u003e\u003ch4\u003eHM 504 A Repair Instructions\u003c\/h4\u003e\u003cul\u003e\u003cli\u003eHM 504 A-2 Aircraft Engine Operating, Maintenance and Partial Overhaul Manual, \u003cem\u003eBetriebs-, Wartungs- und Teilüberholungsvorschrift\u003c\/em\u003e (German Language)\u003c\/li\u003e\u003c\/ul\u003e\u003ch4\u003eHM 504 A Illustrated Parts Catalog\u003c\/h4\u003e\u003cul\u003e\u003cli\u003eHM 504 A-2 Aircraft Engine Operating Instruction and Illustrated Parts Catalog, \u003cem\u003eBetriebsanweisung und Ersatzteilliste\u003c\/em\u003e (German Language)\u003c\/li\u003e\u003c\/ul\u003e\u003ch4\u003eHM 504 A Technical Publications\u003c\/h4\u003e\u003cul\u003e\n\u003cli\u003eHM 504 A-2 Aircraft Engine Technical Textbook Volume 23, \u003cem\u003eLuftfahrt-Lehrbücherei Band 23\u003c\/em\u003e (German Language)\u003c\/li\u003e\n\u003cli\u003eHM 504 Aircraft Engine Description from Arado Company Publication, \u003cem\u003eWerksschrift\u003c\/em\u003e (German Language)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch4\u003eHM 504 A Technical Reports \u0026amp; Certificates\u003c\/h4\u003e\u003cul\u003e\u003cli\u003eHM 504 A Aircraft Engine Data Card, \u003cem\u003eMotoren-Karte\u003c\/em\u003e (German Language)\u003c\/li\u003e\u003c\/ul\u003e\u003chr\u003e\u003ch3\u003eNo-Variant Manual — 1 Document\u003c\/h3\u003e\u003ch4\u003eHM 504 Engine Subsystems\u003c\/h4\u003e\u003cul\u003e\u003cli\u003eSUM-Vergaser 762 Carburetor Description and Illustrated Parts Catalog, \u003cem\u003eSUM-Vergaser 762 für HM 504\u003c\/em\u003e (German Language)\u003c\/li\u003e\u003c\/ul\u003e\u003chr\u003e\u003ch3\u003eAbout the Hirth HM 504\u003c\/h3\u003e\u003ch4\u003eHistorical Background\u003c\/h4\u003e\u003cp\u003eFirst introduced around \u003cstrong\u003e1934\u003c\/strong\u003e as part of the Hirth Motoren “500” engine family, the HM 504 was produced through approximately 1945 with an estimated \u003cstrong\u003e6,000 units\u003c\/strong\u003e built. It powered primary trainers including the \u003cstrong\u003eBücker Bü 131 Jungmann\u003c\/strong\u003e and \u003cstrong\u003eBücker Bü 181 Bestmann\u003c\/strong\u003e for the Luftwaffe, and civilian types including the \u003cstrong\u003eArado Ar 79\u003c\/strong\u003e and \u003cstrong\u003eKlemm Kl 35\u003c\/strong\u003e. The engine was licensed to Japan as the \u003cstrong\u003eHitachi Hatsukaze Model 11\u003c\/strong\u003e, seeing wartime and post-war use in training and liaison aircraft.\u003c\/p\u003e\u003ch4\u003eTechnical Specifications\u003c\/h4\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eType:\u003c\/strong\u003e Inverted inline, 4-stroke air-cooled piston engine\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConfiguration:\u003c\/strong\u003e 4-cylinder inline (inverted)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDisplacement:\u003c\/strong\u003e 3.98 L (243 cu in)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBore × Stroke:\u003c\/strong\u003e 105 mm × 115 mm (4.128 in × 4.52 in)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePower Output:\u003c\/strong\u003e 88.7–105 hp at 2,400–2,530 RPM\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompression Ratio:\u003c\/strong\u003e 6.2:1\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 123.8 kg (273 lbs)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFuel:\u003c\/strong\u003e 77–80 octane aviation gasoline\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch4\u003eEngineering Distinction\u003c\/h4\u003e\u003cp\u003eThe HM 504 features a cast magnesium alloy (\u003cem\u003eElektron\u003c\/em\u003e) crankcase for exceptional weight reduction and the patented \u003cstrong\u003eHirth built-up crankshaft\u003c\/strong\u003e supported throughout by roller bearings — delivering outstanding power-to-weight ratio and low oil consumption for its era.\u003c\/p\u003e\u003ch4\u003eCurrent Status\u003c\/h4\u003e\u003cp\u003eThe HM 504 remains \u003cstrong\u003eairworthy in restored vintage aircraft\u003c\/strong\u003e including the Bücker Bü 131 Jungmann and Bü 181 Bestmann, maintained under legacy Airworthiness Directives for vintage\/historical restoration. Various independent overhaul shops and heritage organizations hold approvals to maintain airworthy engines in restored historical airframes.\u003c\/p\u003e\u003chr\u003e\u003cp\u003e\u003cem\u003eThis is an archival, static-copy edition fixed at its original publication date. Intended for historical reference, flight simulation, museum restoration, and educational use only. Not approved for active airworthiness maintenance under FAA 14 CFR § 43.13, EASA Part-M, or equivalent international regulations. Operators of active aircraft must use current, revision-controlled publications from the Type Certificate holder or an authorized distributor.\u003c\/em\u003e\u003c\/p\u003e\u003cp\u003e⚠️ \u003cstrong\u003eRegulatory Notice:\u003c\/strong\u003e Under FAA 14 CFR § 43.13 and EASA Part-M, any mechanic performing maintenance on an active aircraft must use current, manufacturer-approved revision-controlled data. This archival document does not satisfy that requirement.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eLiving Collections with Free Lifetime Updates — Please review our Disclaimer and Export Notice before purchasing.\u003c\/strong\u003e\u003c\/p\u003e","brand":"Online Aviation Library","offers":[{"title":"Default Title","offer_id":53443957391707,"sku":null,"price":30.0,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0955\/4788\/3867\/files\/hirth-hm-504-promotional-banner.png?v=1782402809","url":"https:\/\/onlineaviationlibrary.com\/products\/hirth-hm-504-engine-manuals-collection","provider":"Online Aviation Library","version":"1.0","type":"link"}